DFS client computers (webfarm nodes in this case) cache the
DFS information for the length of time that you specify. This should not be
too low or you will have too much traffic to the Namespace server, but it
should not be too high or changes to the namespace and failbacks to a restored
server will take a long time to be noticed. It is up to your environment what
you want to set this at, but in every situation it is important to know that
there is some caching that takes place.
Make sure to keep in mind that adding a new folder to your
DFS namespace will not be noticed immediately. You can force the DFS client
cache to be cleared by running dfsutil /PktFlush from the client server. The dfsutil.exe
is a tool that is available in the Windows Server 2003 /support/tools folder of
the installation CD. I simply copy that file to C:\Windows\System32 and I can
run dfsutil from the command prompt.
When setting up new sites, make sure to wait until the new
site has been recognized by all of the webfarm nodes or force a cache flush
from all of the nodes before attempting to set up or update the site.